component
PCA9536
Public Unreviewedby Ray
TI 4-bit I2C/SMBus I/O expander, SOIC-8. Four configurable I/O pins on a fixed I2C address, 2.3-5.5 V. Datasheet-verified.
3D Model
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Symbol & Footprint
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Datasheet
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README
markdownPCA9536
Texas Instruments · I2C I/O expander · SOIC-8
Adds four general-purpose I/O pins to a host over I2C/SMBus. Each of the four pins (P0-P3) is independently set as input or output through a configuration register, and the host reads or drives them over a two-wire bus at a fixed address, so a microcontroller short on pins gains four more without extra wiring. Power-on default is all inputs. A small, cheap way to break out a handful of switches, LEDs, or enable lines.
Pinout
| Pin | Name | Type | Function |
|---|---|---|---|
| 1 | P0 | bidirectional | P-port bit 0. Push-pull bidirectional I/O; configurable as input or output via the Configuration register. Powers up as an input with a weak pull-up to VCC. High-current drive (up to ~25 mA sink) sufficient for direct LED drive. |
| 2 | P1 | bidirectional | P-port bit 1. Push-pull bidirectional I/O; configurable as input or output via the Configuration register. Powers up as an input with a weak pull-up to VCC. |
| 3 | P2 | bidirectional | P-port bit 2. Push-pull bidirectional I/O; configurable as input or output via the Configuration register. Powers up as an input with a weak pull-up to VCC. |
| 4 | GND | power_in | Device ground return. Connect to the system ground plane. |
| 5 | P3 | bidirectional | P-port bit 3. Push-pull bidirectional I/O; configurable as input or output via the Configuration register. Powers up as an input with a weak pull-up to VCC. |
| 6 | SCL | input | I2C serial clock input. Open-drain bus line; connect to VCC through an external pull-up resistor. Supports standard mode (100 kHz) and fast mode (400 kHz). |
| 7 | SDA | bidirectional | I2C serial data line. Open-drain bidirectional bus; connect to VCC through an external pull-up resistor. |
| 8 | VCC | power_in | Supply voltage input, 2.3 V to 5.5 V. Bypass locally with a ceramic decoupling capacitor to GND. |
Key specifications
| Parameter | Value |
|---|---|
| Type | 4-bit I2C / SMBus I/O expander |
| Interface | I2C / SMBus (fixed address) |
| I/O | 4 pins (P0-P3), each input or output |
| Supply | 2.3-5.5 V |
| Bus speed | Up to 400 kHz |
| Default | All I/O as inputs at power-on |
| Package | SOIC-8 |
Ordering variants
Same part, different packaging or reel option.
PCA9536D (SOIC-8, tube)PCA9536DR (SOIC-8, tape & reel)PCA9536DGKR (VSSOP-8)
CAD (KiCad official)
- Symbol:
Interface_Expansion:PCA9536D (KiCad official) - Footprint:
Package_SO:SOIC-8_3.9x4.9mm_P1.27mm - 3D model: SOIC-8 (KiCad packages3D, STEP)
Provenance
Data extracted from the manufacturer datasheet, not a distributor listing:
- Datasheet: Texas Instruments datasheet (35 pp, sha256
bc9e7a06865817ab, retrieved 2026-08-17, tier: manufacturer) - Extractor:
ds2sf(Claude). Every pin and dimension is cited to a datasheet page; it refuses to fabricate. - CAD: KiCad official libraries (CC-BY-SA 4.0).